This section provides background information relating to the present disclosure, which is not necessarily prior art.
In a time division duplex (TDD) wireless communication system supported by the long term evolution (LTE) technology, 7 types of different non-symmetric uplink/downlink configurations can be provided. These uplink/downlink configurations may be provided downlink subframes of 40% to 90%, and have flexible service adaptability.
For the 7 types of uplink/downlink configurations, it is stipulated in the current standard the uplink/downlink hybrid automatic repeat request (HARQ) time sequence and uplink/downlink HARQ parallel process numbers for different configurations. In which, the uplink HARQ time sequence includes a schedule UL grant time sequence for the physical uplink shared channel (PUSCH) and a feedback physical hybrid repeat request indicator channel (PHICH) time sequence for the PUSCH, and the downlink HARQ time sequence includes feedback ACK/NACK time sequence for the physical downlink shared channel (PDSCH).
In the current TDD wireless communication system, in order to reduce interference between cells and decrease the management complexity, the same uplink/downlink configuration will be set statically for cells in the whole network. Under a homogeneous network, in case of covering using a macro base station, since the macro base station provides service for many users and the statistic law for the covered regions is smooth and consistent, the method of statically setting the same uplink/downlink configuration for the cells in the whole network is appropriate. However, under a heterogeneous network, a lot of low power access points are introduced, for example micro base stations, pico base stations, home base stations and remote radio units. Since the low power access points provide service for a few users, generally cover via hot spots, and uplink/downlink service amount of its covered regions changes dynamically and significantly, uplink/downlink service amounts between different low power access points are different significantly. In this case, adopting the above mentioned solution of the static and same configuration in the whole network will influence the improvement of the throughput of the heterogeneous network.
A dynamic TDD uplink/downlink configuration having flexible service self-adaptability may be conceived. As compared with the conventional static or semi-static TDD uplink/downlink configuration, in case of the dynamic TDD uplink/downlink configuration, appropriate uplink/downlink configuration is selected dynamically based on the service amount change condition by various cells, thereby the adaptability and the flexibility is stronger.
In the other aspect, since the uplink/downlink configuration used by each cell dynamically changes as the service amount of the cell changes, the same cell may use different uplink/downlink configurations in different time. The HARQ time sequence solution stipulated in the current standard may not be applicable for the case that the previous and next uplink/downlink configurations change.